This invention relates to the recovery of the carbohydrate fraction, as well as other useful products, from carbohydrate-containing products, particularly molasses.
The art has long been aware that a host of carbohydrate-containing products exist from which can be derived all or part of the desirable carbohydrate content thereof. Products such as fruit juices, cane and beet sugar juices, starch hydrolysates, hardwood sulfite liquors, whey and the like present attractive source materials for carbohydrates such as sucrose fructose, glucose, invert, sugar lactose and xylose. In many cases, however, the low efficiency of prior art separation processes has not justified the expense typically encountered in such methods. Compounding this economic disadvantage has been the inability to obtain additional useful products from these source materials, and hence offset the costs of carbohydrate recovery, without the need for still further extensive separation techniques.
The foregoing problems are particularly acute in the field of sugar refining wherein enormous quantities of "by-products" such as molasses result from the sucrose production process. While molasses is known to contain many useful products, including sucrose, fructose, glucose, invert sugar and inorganic salts, attempts to recover these have been hampered by the inability to achieve any economically significant removal of these valuable products.
The production of sugars such as refined sucrose may begin with either sugar cane or sugar beets as source materials therefor. While processing steps designed to yield substantially pure sucrose differ depending upon the sugar source utilized, a common by-product of these processes is molasses. Molasses may be generated at a number of places in the overall sugar process and is not, therefore, of any absolutely fixed composition. As understood by the art, however, molasses is used generally to define the mother liquor remaining after sucrose has been crystallized out of solution. Molasses will generally contain sucrose, glucose and fructose, inorganic salts, and organic non-sugar compounds. The composition of molasses will depend upon processing conditions, the particular sugar source utilized, and the point in the process from which the molasses is taken off.
While not limited by definition, molasses typically and practically defines a sugar solution wherein, due to the depletion of sucrose, the build-up of non-sucrose solids, and the increased viscosity of the mother liquor, it is no longer possible to crystallize sufficiently pure sucrose therefrom. This type molasses is generally referred to as "final molasses" or "blackstrap molasses." Final molasses has found some useful outlets. For example, it has been utilized as a source of yeast, vinegar and various organic chemicals, such as alcohols, through fermentation. However, technological advances resulting in the more economic synthesis of these products has minimized the importance of molasses as a chemical source. While final molasses is not generally considered suitable for human consumption, molasses generated from earlier stages in the operation of sugar factories (e.g. first and second molasses) have been used for many years as food and as components of bakery and confectionary items. Rarely, however, are molasses used in foods in such quantities as to afford a significant market for the vast quantity of molasses produced in sugar factories.
By far the major use for molasses such as final or blackstrap molases is as a direct feed for ruminant animals and as a raw material for feed compositions. However, in excessive amounts molasses acts as a laxative, thus being a limiting factor for daily consumption.
In some areas of the world molasses has found use as a fertilizer. However, this use of molasses has proven to be economic only in those areas where there is no ready market for molasses.
Molasses from beet sugar processes have long been treated to remove sugars therefrom. The most widely utilized process for desugaring is the Steffen process involving the addition of lime to a dilute molasses solution. While the Steffen process is generally capable of recovering up to 95% of the sugar in beet molasses, it is not generally applicable to the treatment of cane molasses because the process substantially destroys invert sugar. Moreover, the Steffen treatment of beet molasses, resulting as it does in only a single product stream -- sugar -- fails to fully utilize other valuable components of molasses. Still further, raffinose, which leads to errors in the polarization analysis for sucrose and adversely influences sucrose crystal growth, is built-up to a large extent in the Steffen process. The art has therefore generally resorted to discarding molasses in Steffen factories for 24 hour periods every one or two weeks. This "discard molasses" is yet another source of molasses requiring an economical outlet.
The prior art has also recognized the general utility of applying the principle of ion-exclusion in separating sugars from feedstocks such as molasses. See, for example, U.S. Pat. No. 2,937,959 to Reents, et al., issued May 24, 1960. Difficulties are encountered, however, in treating molasses such as blackstrap wherein the effectiveness of the exclusion resin progressively decreases with time. Moreover, considerable problems arise in attempting to practice these techniques on a commercial scale.
It is accordingly an object of this invention to provide a process useful in the treatment of carbohydrate-containing materials to isolate and remove the carbohydrate fraction thereof as well as to effectively recover and utilize other useful products therefrom.
Another object of this invention is to treat molasses to recover useful products therefrom.
A further object of this invention is to treat molasses, without regard for the source thereof, to obtain a variety of useful products which enhance the complete utilization of molasses.
Yet another object of this invention is to treat molasses to produce a product useful as a sugar source; a product useful as a fertilizer; and a product useful as an animal feedstock.
Still another object of this invention is to produce the above-mentioned products in quantities relative to their economic and practical utilization.
Another object of this invention is to clarify solutions of carbohydrate-containing materials, particularly blackstrap molasses.
These and other objects will become more apparent upon reading the more detailed description which follows.